Three wildlife conservation groups filed a federal lawsuit Monday to stop Maine’s fur-trapping season in an effort to prevent the accidental killing of Canada lynx, a federally protected species.

The nonprofit organizations filed a joint lawsuit in U.S. District Court in Bangor against the U.S. Fish and Wildlife Service, accusing the federal agency of allowing Maine to issue trapping licenses for fur-bearing animals such as coyote, fox and mink, even though Maine’s permitting process lacks the protections for lynx set out by the Endangered Species Act.

The three groups – the California-based Center for Biological Diversity, the Penobscot-based Wildlife Alliance of Maine and the Washington D.C.-based Animal Welfare Institute – have asked a federal judge to stop the 10-week trapping season, which runs from Oct. 15 to the end of the year.

Lynx are protected animals under the Endangered Species Act and hunting them intentionally is illegal, but a total of 70 lynx were trapped in Maine from 1999 to 2012, according to the lawsuit.

“Sickening reports of lynx deaths and injuries, as well as an unknown number of unreported incidents, show that the state and feds are doing a haphazard job providing lynx the protections required under the law,” Daryl DeJoy, executive director of the Wildlife Alliance of Maine, said in a written statement announcing the lawsuit. “We hope that this lawsuit brings necessary changes to Maine’s trapping programs that will help ensure the lynx’s survival in Maine.”

The organizations make three claims against the U.S. Fish and Wildlife Service and its director, Daniel Ashe, saying that the federal agency violated the Endangered Species Act in different ways. In a fourth claim, they accuse the agency of violating the National Environmental Policy Act.

The groups argue that with two lynx killed since the federal agency approved Maine’s permitting process in November, the state already is at risk of exceeding the number of accidental lynx deaths permitted over a 15-year period. The lawsuit says that over 15 years, Maine’s permit allows no more than three lynx to be killed, nine severely injured but able to be rehabilitated and 183 that may be trapped with minor injuries and released.

The Maine Department of Inland Fisheries & Wildlife shut down trapping for most above-ground species throughout northern Maine in early December in response to the lynx trapping incidents.

Gavin Shire, a U.S. Fish and Wildlife Service spokesman, said the agency has a policy of not commenting on issues under pending litigation.

No one from the state Department of Inland Fisheries & Wildlife responded to a voice mail message seeking comment Monday.

In January, Maine wildlife officials said that the state’s lynx population – estimated at between 750 and 1,000 adults – is growing and helps explain the record 20-plus lynx inadvertently caught in traps during last year’s season.

The lawsuit comes as the federal agency is already reviewing whether there are adequate protections for the “threatened” Canada lynx, whose territory once had breeding populations throughout the Northeast but now exists only in northern Maine.

Habitat is a key consideration in Maine because the vast majority of the state’s forests are privately owned and managed for timberland. That makes managing for lynx habitat more challenging in Maine than in the West, where many of the forests inhabited by lynx are federally owned.

As a threatened species, lynx are protected from harassment or harm under federal law. But in November, the U.S. Fish and Wildlife Service issued Maine a permit – known as an “incidental take permit” – that allows trapping for other species to continue in areas of the state inhabited by the wildcats.

At the end of the review, the U.S. Fish and Wildlife Service will decide whether the lynx should remain a “threatened” species, be listed as “endangered” or be removed from the endangered species list. The federal review will examine, among other factors, the latest lynx population trends throughout its range, as well as whether there is adequate habitat protection.

For DeJoy, the Fish and Wildlife Service’s recent actions have marked a step backward in protections for lynx since a previous lawsuit before the same Maine federal court ended in 2007 with a consent decree aimed at minimizing accidental lynx trapping.

DeJoy said that after the federal agency accepted the state’s permit application last November, his group requested thousands of pages of documents and emails exchanged between the Maine agency and federal agency under the federal Freedom of Information Act.

He said he expects those documents will be introduced as evidence in the lawsuit to show collusion between the two government agencies to cut corners and weaken wildlife protections.

Lynx can weigh up to 30 pounds, and are similar in size and appearance to the much more common bobcat. Unlike bobcat, however, lynx have large, padded feet that allow them to pursue their favorite prey, the snowshoe hare, in deep snow. Lynx populations are often tied to hare abundance, with its cyclical population spikes.